Table 2.

Comparison of carboxylation enzymes in engineered E. coli strains

Strain	Cell yield (g/l)	Succinate (g/l·h)	Enzyme activity* [U·mg protein −1]				pck mRNA	G to A change
			Pck	Ppc	MaeA	MaeB
E. coli ATCC	2.0 ± 0.2	0.12 ± 0.01	0.30 ± 0.02	0.020 ± 0.002	ND	<0.01	1.0	No
KJ012‡	0.3 ± 0.1	0.04 ± 0.01	0.16 ± 0.01	0.025 ± 0.002	0.005 ± 0.001	<0.01	0.2	No
KJ017	1.7 ± 0.1	0.35 ± 0.03	0.70 ± 0.07	0.017 ± 0.001	0.012 ± 0.001	<0.01	2.7	No
KJ060	2.2 ± 0.1	0.90 ± 0.04	8.4 ± 0.7	0.030 ± 0.003	0.011 ± 0.002	<0.01	7.2	Yes
KJ071	1.5 ± 0.1	0.33 ± 0.04	0.68 ± 0.07	0.023 ± 0.002	0.010 ± 0.001	<0.01	2.5	No
KJ073	2.3 ± 0.1	0.82 ± 0.01	7.3 ± 0.5	0.027 ± 0.02	0.021 ± 0.001	<0.01	8.4	Yes
E. coli K12†	ND	ND	0.14	0.14	ND	ND	ND	ND
Actinobacillus succinogenes†	ND	ND	4.7	0.01	ND	ND	ND	ND

*Pck, PEP carboxykinase; Ppc, PEP carboxylase; MaeA, NADH-linked malic enzyme; MaeB, NADPH-linked malic enzyme; ND, not determined. Crude extract was prepared from mid-log cells during fleaker fermentation.

^†Data from VanderWerf et al. (5).

^‡Poor growth.